I created a trakt account earlier this year, for syncing my watched progress. Now with iCloud sync can I disable my trakt account or do I still need that?
You’ll still need it. Trakt has the benefit of also working on different apps so if you, say, buy an Android TV and use Kodi you can sync your Trakt between that and Infuse.
I only use apple products, so I dont need it?
Trakt allows watched progress and history to be synced between devices. For a variety of reasons, this info is not currently synced to iCloud.